Systems and methods for improving catheter hole array efficiency

ABSTRACT

A peripheral catheter having a catheter tip diffuser for reducing an exit velocity of an infusant within the catheter. Pluralities of diffusion side holes are provided on the tip portion of the catheter. Some examples further include pluralities of annularly arranged, staggered diffusion holes provided on the tip portion of an intravenous catheter to streamline infusant issued from the diffusion holes. An inner surface of each diffusion hole is further angled relative to the inner surface of the catheter lumen such that an infusant within the lumen exits the catheter though the diffusion holes at an angle less than 90°.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/046,843, filed Apr. 22, 2008, entitled POWER PIVC HOLE ARRAYEFFICIENCY IMPROVEMENTS, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to vascular infusion systems andcomponents, including catheter assemblies and devices used with catheterassemblies. In particular, the present invention relates to systems andmethods for improving catheter hole array efficiency to provide enhancedinfusion flowrates, lower system pressures, and reduced catheter exitjet velocities.

Vascular access devices are used for communicating fluid with theanatomy of a patient. For example, vascular access devices, such ascatheters, are commonly used for infusing fluid, such as salinesolution, various medicaments, and/or total parenteral nutrition, into apatient, withdrawing blood from a patient, and/or monitoring variousparameters of the patient's vascular system.

A variety of clinical circumstances, including massive trauma, majorsurgical procedures, massive burns, and certain disease states, such aspancreatitis and diabetic ketoacidosis, can produce profound circulatoryvolume depletion. This depletion can be caused either from actual bloodloss or from internal fluid imbalance. In these clinical settings, it isfrequently necessary to infuse blood and/or other fluid rapidly into apatient to avert serious consequences.

Additionally, the ability to inject large quantities of fluid in a rapidmanner may be desirable for certain other medical and diagnosticprocedures. For example, some diagnostic imaging procedures utilizecontrast media enhancement to improve lesion conspicuity in an effort toincrease early diagnostic yield. These procedures necessitate viscouscontrast media be injected by a specialized “power injector” pumpintravenously at very high flow rates, which establishes a contrastbolus or small plug of contrast media in the bloodstream of the patientwhich results in enhanced image quality.

Power injection procedures generate high pressures within the infusionsystem, thereby requiring specialized vascular access devices, extensionsets, media transfer set, pump syringes, and bulk or pre-filled contrastmedia syringes. As the concentration (and thereby viscosity) andinfusion rate of the contrast media are increased, bolus density alsoincreases resulting in better image quality via computed tomography (CT)attenuation. Therefore, a current trend in healthcare is to increase thebolus density of the contrast media by increasing both the concentrationof the contrast media and the rate at which the media is infused intothe patient, all of which ultimately drives system pressure requirementshigher.

Intravenous infusion rates may be defined as either routine, generallyup to 999 cubic centimeters per hour (cc/hr), or rapid, generallybetween about 999 cc/hr and 90,000 cc/hr (1.5 liters per minute) orhigher. For some diagnostic procedures utilizing viscous contrast media,an injection rate of about 1 to 10 ml/second is needed to ensuresufficient bolus concentration. Power injections of viscous media atthis injection rate produce significant back pressure within theinfusion system that commonly results in a failure of the infusionsystem components.

Traditionally, rapid infusion therapy entails the use of an intravenouscatheter attached to a peristaltic pump and a fluid source. A patient isinfused as a tip portion of the catheter is inserted into thevasculature of a patient and the pump forces a fluid through thecatheter and into the patient's vein. Current rapid infusion therapiesutilize a catheter and catheter tip with geometries identical to thoseused with traditional, routine infusion rates. These geometries includea tapering catheter tip such that the fluid is accelerated as the fluidmoves through the catheter tip and exits into a patient's vasculature.This acceleration of the infused fluid is undesirable for severalreasons.

For example, the tapered catheter results in a greater backpressure forthe remainder of the catheter assembly. This effect is undesirable dueto the limitations of the pumping capacity of the infusion pump as wellas the limited structural integrity of the components and subcomponentsof the infusion system. For example, if the backpressure becomes toogreat, the pump's efficiency may decrease and certain seals orconnections within the infusion system may fail. Additionally, the fluidacceleration in the catheter tip results in a recoil force that maycause the catheter tip to shift within the patient's vein therebydisplacing the catheter and/or damaging the patient's vein and/orinjection site. Fluid acceleration also increases the jet velocity ofthe infusant at the tip of the catheter. In some procedures, the fluidjet may pierce the patient's vein wall thereby leading to extravasationor infiltration. Not only is this uncomfortable and painful to thepatient, but infiltration may also prevent the patient from receivingthe needed therapy.

Accordingly, the problem of increased exit velocity of an infusantduring rapid infusion procedures remains to be solved. Thus, the presentdisclosure presents systems and methods to reduce the exit velocity ofan infusant while maintaining an increased rate of infusion, as isdesirable during rapid infusion procedures.

BRIEF SUMMARY OF THE INVENTION

The systems and methods of the present disclosure have been developed inresponse to problems and needs in the art that have not yet been fullyresolved by currently available infusion systems and methods. Thus,these systems and methods are developed to provide for safer and moreefficient rapid infusion procedures.

One aspect of the present invention provides an improved vascular accessdevice for use in combination with a vascular infusion system capable ofrapidly delivering an infusant to the vascular system of a patient. Thevascular access device generally includes an intravenous catheterconfigured to access the vascular system of a patient. The intravenouscatheter is coupled to the vascular infusion system via a section ofintravenous tubing. The material of the intravenous catheter may includea polymer or metallic material compatible with infusion procedures.

In some embodiments, a tip portion of the intravenous catheter ismodified to include a plurality of diffusion holes. The tip portiongenerally comprises a tapered profile, wherein the outer and innersurface of the tip taper towards the distal end of the catheter. Thetapered outer surface provides a smooth transition between the narrowdiameter of the catheter tip opening and the larger diameter of thecatheter tubing. Thus, as the tip of the catheter is introduced into thevein of a patient, the tapered outer surface facilitates easy insertionof the catheter through the access hole. The tapered inner surface isgenerally provided to tightly contact the outer surface of an introducerneedle housed within the lumen of the catheter. The introducer needle isprovided to create an opening into the vein of patient through which thecatheter tip is inserted. The tapered inner surface ensures a tight sealbetween the inner surface of the catheter and the outer surface of theneedle. Following placement of the catheter, the introducer needle isremoved.

As an infusant passes through the tapered portion of the inner surface,the fluid flow of the infusant is accelerated due to the decreasedvolume through the tapered tip. Thus, in some embodiments a plurality ofdiffusion holes are formed through the wall thickness of the intravenouscatheter so as to provide a plurality of pathways through the wall ofthe intravenous catheter. Thus, as infusant flows through the cathetertoward the tip of the catheter, a portion of the bulk flow through thecatheter is diverted through the diffusion holes rather than through themain opening of the catheter tip. As such, the pressure within theinfusion system is reduced as compared to systems incorporating standardintravenous catheter. Additionally, the plurality of diffusion holesreduce the jet velocity issued from the tip of the catheter, therebyenabling increased flow rates as required by some diagnostic procedureswithout additional damage to the vein wall.

In some embodiments, the diffusions holes are arranged on the cathetertip in a staggered array such that an upstream diffusion hole isunaligned with a downstream hole. As such, the fluid flow of an infusantthat issues from a downstream diffusion hole is not disturbed by thefluid flow of an infusant that issues from an upstream diffusion hole.This feature provides increased flow efficiency through downstreamdiffusion holes.

In some embodiments of the present invention, a first set of diffusionholes is disposed in a first annular ring at an upstream, axial positionof the catheter tip. A second set of diffusion holes is further disposedin a second annular ring at an axial position of the catheter tip thatis downstream from the first annular ring. In some embodiments, theholes of the first annular ring are staggered from the holes of thesecond annular ring so as to be generally unaligned. In otherembodiments, the holes of the first annular ring are axially staggeredfrom the holes of the second annular ring from about 15° to about 60°.Finally, in some embodiments the holes of the first annular ring areaxially staggered from the holes of the second annular ring about 45°.

In some embodiments, the diffusion holes are provided through thecatheter wall at a predetermined bore angle. Specifically, the diffusionholes of the present invention include an inner wall surface that may beangled relative to the inner surface of the catheter lumen. In someembodiments, the inner surface of a diffusion hole is oriented to anacute angle relative to the inner surface of the catheter lumen. Inother embodiments, an inner surface of the diffusion hole is oriented toan angle from about 15° to about 75° relative to the inner surface ofthe catheter lumen. In some embodiments, the bore angle of the diffusionhole is selected so as to optimize flow efficiency through the diffusionhole, catheter tension within the vein, centralized positioning of thecatheter tip within the vein, and reduction of system pressure and tipjet velocity within an infusion system.

The present invention further includes methods for manufacturing anintravenous catheter for diffusing an infusant. Some methods include thesteps of providing an intravenous catheter and forming a plurality ofstaggered holes through the wall thickness of the intravenous catheter.Some methods of the present invention further include using a laserdrill to provide the various staggered holes.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In order that the manner in which the above-recited and other featuresand advantages of the invention are obtained will be readily understood,a more particular description of the invention briefly described abovewill be rendered by reference to specific embodiments thereof which areillustrated in the appended drawings. These drawings depict only typicalembodiments of the invention and are not therefore to be considered tolimit the scope of the invention.

FIG. 1 is a perspective view of an infusion system in accordance with arepresentative embodiment of the present invention.

FIG. 2 is a detailed perspective view of a catheter in accordance with arepresentative embodiment of the present invention.

FIG. 3A is a perspective view of a catheter tip in accordance with arepresentative embodiment of the present invention.

FIG. 3B is a cross-section side view of the catheter tip of FIG. 3A inaccordance with a representative embodiment of the present invention.

FIG. 4A is a perspective view of a catheter tip in accordance with arepresentative embodiment of the present invention.

FIG. 4B is a cross-section side view of a catheter tip in accordancewith a representative embodiment of the present invention.

FIG. 5 is a graphical representation of jet tip velocities at variousflow rates in accordance with representative embodiments of the presentinvention.

FIG. 6 is a graphical representation of system pressures at various flowrates in accordance with representative embodiments of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

The presently preferred embodiments of the present invention will bebest understood by reference to the drawings, wherein like referencenumbers indicate identical or functionally similar elements. It will bereadily understood that the components of the present invention, asgenerally described and illustrated in the figures herein, could bearranged and designed in a wide variety of different configurations.Thus, the following more detailed description, as represented in thefigures, is not intended to limit the scope of the invention as claimed,but is merely representative of presently preferred embodiments of theinvention.

The systems and methods of the present invention are generally designedfor use in combination with a vascular infusion system capable ofrapidly delivering an infusant to the vascular system of a patient.Referring now to FIG. 1, a vascular infusion system 100 is shown, inaccordance with a representative embodiment of the present invention.Infusion systems of this type are commonly configured to operate atinternal pressures up to 2000 psi. Many systems operate in the range of75 to 2000 psi, while specific devices of this type operate at 100, 200,and 300 psi. The vascular infusion system 100 comprises a vascularaccess device 112 coupled to an injector pump 120 via a coiled extensionset 130. In some embodiments, the infusion system 100 further comprisesa safety device 140 positioned between the vascular access device 112and the injector pump 120. In some embodiments, a safety device 140 isprovided to automatically occlude the fluid path of the infusion system100, thereby preventing excessive pressure buildup in downstreaminfusion components.

An injector pump 120 generally comprises a fluid pumping apparatusconfigured to rapidly deliver an infusant, such as blood, medicaments,and CT scan contrast agents to a patient's vascular system. Desirableinfusants may also include various fluids often of high viscosity asrequired for medical and diagnostic procedures. In some embodiments, theinjector pump 120 comprises a power injector capable of delivering aninfusant to a patient at flow rates from about 10 mL/hour up to about1200 mL/minute. In some embodiments, a high infusion flow rate isdesirable for medical procedures which require enhanced bolus density ofan infusant in a patient's vascular system. For example, a trend indiagnostic imaging procedures is to utilize contrast media enhancement,which requires more viscous contrast media to be pushed into a patientat a higher flow rate, thereby resulting in increased image quality.Thus, in some embodiments an injector pump 120 and a vascular accessdevice 112 are selected to compatibly achieve a desired infusion flowrate.

A coiled extension set 130 generally comprises flexible or semi-flexiblepolymer tubing configured to deliver an infusant from the injector pump120 to the vascular access device 112. The extension set 130 includes afirst coupler 132 for connecting the extension set 130 to a downstreamdevice 112 or 140. The extension set 130 also includes a second coupler134 for connecting the extension set 130 to the injector pump 120. Acoiled configuration of the extension set 130 generally preventsundesirable kinking or occlusion of the set 130 during infusionprocedures. However, one of skill in the art will appreciate that theextension set 130 may include any configuration capable of efficientlydelivering an infusant from an injector pump 120 to the patient via avascular access device 112. In some embodiments, the extension set 130is coupled between a syringe and a vascular access device whereby aninfusant is manually injected into a patient. In other embodiments, theinfusion system comprises only a syringe and a vascular access device,in accordance with the present invention.

The vascular access device 112 generally comprises a peripheralintravenous catheter 114. A peripheral intravenous catheter 114 inaccordance with the present invention generally comprises a short ortruncated catheter (usually 13 mm to 52 mm) that is inserted into asmall peripheral vein. Peripheral intravenous catheters 114 aretypically designed for temporary placement. The short length of thecatheter 114 facilitates convenient placement of the catheter but makesthem prone to premature dislodging from the vein due to movement of thepatient and/or recoil forces experienced during infusion procedures.Furthermore, unlike midline or central peripheral catheters, peripheralintravenous catheters 114 in accordance with the present inventioncomprise a tapered catheter tip 146 to accommodate use with anintroducer needle (not shown) designed to aid in insertion of thecatheter 114.

An introducer needle is typically inserted through the catheter 114 suchthat a tip of the needle extends beyond the tapered tip 146. The taperedgeometry of the tapered tip 146 conforms tightly to the outer surface ofthe introducer needle. Both the outer surface and the inner surface ofthe tip 146 are tapered towards the distal end of the catheter 114. Theouter surface of the tip 146 is tapered to provide a smooth transitionfrom the smaller profile of the introducer needle to the larger profileof the catheter outer diameter. Insertion of the introducer needle intothe vein of the patient provides an opening into the vein through whichthe tapered tip 146 of the catheter 114 is inserted. The tapered outersurface of the tip 146 enables easy insertion of the catheter 114 intothe opening. Once the peripheral intravenous catheter 114 is insertedinto the vein of the patient, the introducer needle (not shown) isremoved from the lumen of the catheter 114 to permit infusion via thecatheter 114.

The tapered inner surface of the tip 146 provides a secure seal betweenthe inner surface of the catheter tip 146 and the outer surface of theintroducer needle (not shown). Additionally, the tapered inner surfaceof the tip 146 causes an acceleration of infusant within the lumen ofthe catheter as the infusant nears and flows through the catheter tip146. Specifics regarding the geometries of the tapered inner surface ofthe tip 146 are provided in connection with FIGS. 3B and 4B below.Following an infusion procedure, the peripheral intravenous catheter 114is simply removed from vein and discarded.

A desired infusant is typically delivered to the catheter 114 via asection of intravenous tubing 116 coupled to the catheter 114. In someembodiments, a y-adapter 118 is coupled to an end of the tubing 116opposite the catheter 114, enabling the vascular access device 112 to becoupled to the remainder of the vascular infusion system 100. One ofskill in the art will appreciate the possible variations and specificfeatures of available vascular access devices 112, as are commonly usedin the medical and research professions. For example, in someembodiments a catheter 114 in accordance with the present invention mayinclude additional access sites, clamps, parallel intravenous lines,valves, couplers, introducer needles, coatings, and/or materials asdesired to fit a specific application.

Referring now to FIG. 2, a catheter 214 is shown in accordance with arepresentative embodiment of the present invention. Catheter 214generally comprises a catheter adapter 218 configured to house a tubularbody member 220. Catheter adapter 218 further includes an inlet port 230that is coupled to a section of intravenous tubing 216. The section ofintravenous tubing 216 is further coupled to upstream infusioncomponents, as shown and described in connection with FIG. 1, above.

The catheter adapter 218 facilitates delivery of an infusant within theintravenous tubing 216 to a patient via the tubular body member 220. Aninner lumen of the catheter adapter 218 is in fluid communication withboth an inner lumen of the intravenous tubing 216 and an inner lumen ofthe tubular body member 220. In some embodiments, catheter adapter 218further comprises an access port 222. The access port 222 is generallyprovided to permit direct access to the inner lumen of the catheteradapter 218. In some embodiments, the access port 222 is accessed via aneedle and a syringe to deliver an infusant to a patient via the tubularbody member 220. In other embodiments, an introducer needle or guidewire is inserted into the access port 222 and advanced through the innerlumen of the tubular body member 220. In some embodiments, a tip portionof the introducer needle or guide wire (not shown) extends beyond a tipportion 240 of the tubular body member 220. As such, the tip portion ofthe introducer needle or guide wire may provide an opening into thevascular system of a patient into which the tubular body member 220 isinserted. Following placement of the tubular body member 220 into thevein of the patient, the introducer needle or guide wire is removed fromthe access port 222 thereby establishing fluid communication between thetubular body member 220, the catheter adapter 218 and the intravenoustubing 216.

In some embodiments, the tubular body member 220 comprises anintravenous catheter. The intravenous catheter 220 generally comprises aflexible or semi-flexible biocompatible material, as commonly used inthe art. In some embodiments, the intravenous catheter 220 comprises apolymer material, such as polypropylene, polystyrene, polyvinylchloride,polytetrafluoroethylene, and the like. In other embodiments, theintravenous catheter 220 comprises a metallic material, such as surgicalsteel, titanium, cobalt steel, and the like.

The tubular body member 220 may comprise any length, where the length isselected based on the intended application of the catheter 214. For someapplications, the tubular body member 220 is inserted into a peripheralvein of the patient. In other applications, the tubular body member 220is inserted into a central vein of the patient. For rapid infusionapplications, the tip portion 240 of the tubular body member 220 ismodified to include a plurality of diffusion holes 250. The diffusionholes 250 are generally provided to divert fluid from the main channelof flow through the inner lumen of the tubular body member 220. As such,the diffusion holes 250 effectually slow the jet of infusant whichissues from the catheter tip 240 during rapid infusion procedures.Additionally, the plurality of diffusion holes 250 increase theaccumulative area of the catheter tip opening 242 to relieve the overallpressure in the vascular infusion system 100.

Referring now to FIG. 3A, a distal end portion 320 of an intravenouscatheter 314 is shown, in accordance with a representative embodiment ofthe present invention. As previously discussed, an external surface ofthe tip 340 is tapered so as to provide a gradual transition from thecatheter opening 342 of the tip 340 to the diameter of the catheter body314. In some embodiments, the tip 340 of the intravenous catheter 314 ismodified to include a plurality of side holes 350. The side holes 350are generally positioned on the tapered tip 340 of the catheter 314 toprovide an access through which infusant within the catheter 314 mayissue. The surface area of the side holes 350 combine with the surfacearea of the lumen opening 342 to increase the overall surface areathrough which an infusant may issue from the tip 340 of the intravenouscatheter 314. The side holes 350 are annularly organized on the tip 340of the intravenous catheter 314 so as to align adjacent holes along acommon axis 360. As such, an upstream hole 356 is directly aligned withdownstream holes 358.

Referring now to FIG. 3B, a cross-sectioned view of the intravenouscatheter 314 of FIG. 3A is shown. As previously discussed, a portion 334of the internal surface of the tip 340 is tapered which causes anacceleration in the fluid flow 390 through the tip 340. The side holes350 of the intravenous catheter 314 are formed through the catheter wall354 such that an inner surface 364 of each hole 350 is oriented at anangle 370 of approximately 90° relative to an inner surface 382 of thecatheter lumen 380. The side holes 350 are generally positioned withinthe tapered portion 334 of the tip 340 such that as the velocity of thefluid flow 390 increases through the tapered portion 334, infusant 394is permitted to issue through the side holes 350. As infusant issuesthrough the side holes 350, fluid pressure within the lumen 380 isdecreased. Additionally, as infusant issues through the side holes 350,tip jet velocity of the infusant also decreases.

Computational fluid dynamic analysis of the 90° side holes 350 revealsthat only a first half 374 of each hole 350 cross section is utilized bythe fluid flow 390. In some embodiments, a second half 376 of the 90°side holes 350 cross section comprises a recirculation eddy 392.Therefore, in some embodiments the 90° side hole 350 configuration maydemonstrate approximately fifty percent flow efficiency through eachside hole 350.

Referring now to FIG. 4A, a distal end portion 420 of an intravenouscatheter 414 is shown in accordance with a representative embodiment ofthe present invention. The intravenous catheter 414 has been modified toinclude a plurality of staggered diffusion holes 450. One having skillin the art will appreciate that the number and dimensions of thediffusion holes 350 and 450 may be varied and adjusted to achieve adesired flow rate, a reduction in tip jet velocity, a reduction invascular damage, and increased bolus density. Diffusion holes 350 and450 are generally provided by manufacturing methods known in the art.For example, in some embodiments the plurality of diffusion holes 350and 450 are provided with a laser drill.

In some embodiments, a selected array of the diffusion holes 450increases the distance between adjacent holes 450 thereby structurallystrengthening the tip 440 of the intravenous catheter 414, as comparedto some linear hole arrays. In other embodiments, a selected array ofthe diffusion holes 450 further streamlines infusant issued from thediffusion holes 450 thereby reducing the energy necessary to divert bulkflow from the main stream of the catheter lumen 490 into the diffusionholes 450.

For example, in some embodiments of the present invention the diffusionholes 450 have been arranged in a staggered configuration, as shown.Accordingly, an upstream hole 456 is unaligned with an adjacent,downstream hole 458. Furthermore, downstream hole 458 is unaligned withan adjacent, downstream hole 460. In some embodiments, upstream hole 456is directly aligned with downstream hole 460 along a common axis 480. Inother embodiments, upstream hole 456, downstream hole 458 and downstreamhole 460 are each unaligned with each other, such that none of the holesare aligned along a common axis. In some embodiments, an upstream hole456 is axially staggered from a downstream hole 458 from about 15° toabout 60°. Finally, in some embodiments, an upstream hole 456 is axiallystaggered from a downstream hole 458 approximately 45°.

The diffusion holes 450 are annularly organized on the tapered portionof the tip 440 of the intravenous catheter 414 in a staggeredconfiguration, as previously discussed. A first annular ring 402comprises a plurality of diffusion holes 450 forming a first upstreamring of diffusion holes. In some embodiments, the holes of the firstannular ring 402 are axially spaced an equal distance from adjacentholes of the first annular ring 402. In other embodiments, a non-uniformaxially spacing is applied to the holes of the first annular ring 402.In some embodiments, a second annular ring 404 is provided downstreamfrom the first annular ring 402, the diffusion holes of the secondannular ring 404 being staggeredly positioned relative to the diffusionholes of the first annular ring 402. Finally, in some embodiments athird annular ring 406 is provided downstream from the second annularring 404, the diffusion holes of the third annular ring 406 beingstaggeredly positioned relative to the diffusion holes of the secondannular ring 404.

A gap 424 is provided between adjacent holes of the first annular ring402. In some embodiments, the gap 424 is provided to accommodate thewidth of downstream hole 458, such that the downstream hole 458 and thegap 424 are aligned along a common axis (not shown). Furthermore, adownstream gap 428 is provided to accommodate the width of an upstreamhole 466, such that the upstream hole 466 and the downstream gap 428 arealigned along a common axis (not shown). The axial alignment of theupstream gap 424 and the downstream hole 458 prevents wake effect due tothe absence of a diffusion hole directly upstream from the downstreamhole 458. Similarly, the axial alignment of the downstream gap 428 andthe upstream hole 466 prevents wake effect due to the absence of adiffusion hole directly downstream from the upstream hole 466.

The staggered configuration of the first, second and third annular rings402, 404 and 406 provides an elongate gap 426 forming a space between anupstream diffusion hole 452 of the first annular ring and an axiallyaligned downstream diffusion hole 454 of the third annular ring 406. Thelength of the elongate gap 426 generally provides sufficient distancebetween an upstream diffusion hole 452 and a downstream diffusion hole454, so that the fluid pressure of an infusant from the upstream hole452 is approximately equal to the fluid pressure of an infusant from thedownstream hole 454. Thus, the staggered configuration of the diffusionholes 450 ensures equal flow efficiency from upstream and downstreamdiffusion holes 452 and 454.

In some embodiments, the diffusion holes 450 are formed through thecatheter wall 474 such that an inner surface 464 of each hole 450 isoriented at an angle 470 that is acute to an inner, tapered surface 482of the catheter lumen 490, as shown in FIG. 4B. In some embodiments, theangle 470 is between about 15° to about 75°. In other embodiments, theangle 470 is approximately 45°.

EXAMPLES

To decrease the amount of contrast media required for a diagnosis, theconcentration of contrast media per unit volume of blood needs to beincreased by increasing the volumetric flow rate of the of contrastmedia without increasing the catheter tip velocity. The elements of thepresent invention achieve these required objectives, as demonstrated inthe examples below.

Example 1 Tip Jet Velocity Comparison

The jet velocities at the tip of a standard catheter are in excess of1,000 in/sec for a 5 ml/sec volumetric flow rate setting, which resultsin a large force applied to the vein wall of a patient. This force istreacherous for patients with non-optimal vein structure provisionsincreasing the likelihood of extravasation or intima damage withincreasing flow rates.

Jet tip velocities of a standard 22 GA×1.00″ catheter (V_tip Current)were compared to a 22 GA×1.00″ catheter (V_tip Ex. 1−V_tip Ex. 4)modified to include a plurality of diffusion holes, as described inconnection with FIGS. 4A and 4B, above. Quadruplicate samples of themodified catheter were tested at flow rates of 1 ml/sec, 2 ml/sec, 3ml/sec, 4 ml/sec, and 5 ml/sec. Tip jet velocity was then recorded foreach sample and compared to the jet velocity of the standard catheter ateach flow rate. The experiment demonstrated that the overall tip jetvelocity of the modified catheter was decreased by 36% over the standardcatheter. The results of the experiment are shown in FIG. 5.

Example 2 System Pressure Comparison

Internal pressures within an infusion system were compared between aninfusion system using a standard 22 GA×1.00″ catheter and an infusionsystem using a 22 GA×1.00″ catheter (P_inj #1 and P_inj #2) modified toinclude a plurality of diffusion holes, as described in connection withFIGS. 4A and 4B, above.

System pressure was measured both within each infusion pump (P_injCurrent, P_inj 1 and P_inj 2) and the inner lumen of each catheter(P_sept Current, P_sept 1 and P_sept 2). System pressure was tested andrecorded at flow rates of 1 ml/sec, 2 ml/sec, 3 ml/sec, 4 ml/sec, and 5ml/sec. System pressures at each flow rate where then graphed, as shownin FIG. 6.

The results of the experiment demonstrate an increase in the volumetricflow rate by decreasing system pressure by nearly 30%, with the greatestreduction in pressure being shown within the lumen of the modifiedcatheters.

Example 3 Computational Fluid Dynamic Analysis

Computation fluid dynamic analysis was conducted on a standard 22GA×1.00″ catheter modified to include a plurality of diffusion holesbored approximately 45° relative to the inner wall surface of thecatheter. The analysis revealed an addition 6% diversion of bulk flowfrom the main stream into the diffusion holes, as compared to a standard22 GA×1.00″ catheter having a plurality of diffusion holes bored 90°relative to the inner wall surface of the catheter. The analysis furtherrevealed a significant increase in fluid flow 492 through the crosssection of the diffusion hole 450, as compared to the straight holes ofthe standard catheter. While the diffusion holes 450 of the presentinvention did show a slight recirculation eddy 494, the recirculationeddy 494 was significantly weaker as compared to the circulation eddy392 of the standard catheter. A representative rendering of the fluidflow 492 is shown in FIG. 4B.

Example 5 Catheter Stabilization and Vein Centering

In standard peripheral intravenous catheters, the inner lumen of thecatheter tapers towards the tip of the catheter resulting in a recoilforce as an infusant accelerates through the constriction. This force isakin to the force felt when holding a fire hose. Like a fire hose, acatheter tip under the compressive recoil force is unstable and canoscillate violently within the vein (also known as catheter whip)causing vein damage, as previously discussed. If enough infusant isturned from the axial direction through diffusion holes, then the recoilforce will become negative and actually pull the catheter tip intotension; the tensioned state of the catheter tip providing greatstability to the inserted catheter. Therefore, in some embodiments thebore angle is strategically selected to balance between increased flowthrough the diffusion holes and decreased recoil force on the cathetertip by reducing the axial direction of infusant flowing through thediffusion holes.

The bore angle further affects the positioning of the catheter withinthe vein. For example, when inserted in to a vein the venous cathetergenerally extends through the skin and into the vein at approximately30°. As such, the tip of the venous catheter commonly contacts or restsagainst the inner wall of the vein opposite the insertion site of thecatheter. As fluid flow increases, high jet velocity from the cathetertip is exerted directly on the inner wall of the vein. However, when thetip of the venous catheter is modified to include diffusion ports, thediverted infusant that issues from the diffusion ports pushes thecatheter tip away from the vein wall resulting in a centralized positionof the catheter tip within the vein. Thus, the jet velocity from the tipis directed into the fluid stream of the vein rather than into the veinwall.

The present invention may be embodied in other specific forms withoutdeparting from its structures, methods, or other essentialcharacteristics as broadly described herein and claimed hereinafter. Thedescribed embodiments are to be considered in all respects only asillustrative, and not restrictive. The scope of the invention is,therefore, indicated by the appended claims, rather than by theforegoing description. All changes that come within the meaning andrange of equivalency of the claims are to be embraced within theirscope.

1. A peripheral catheter, comprising: a tubular body member of apredetermined diameter and wall thickness, the tubular body memberhaving a proximal end, a distal end and a lumen extending therebetween,the tubular body member further having a truncated length sufficient toaccess a peripheral vein of a patient; a tapered tip forming the distalend of the tubular body member; and a plurality of holes positioned onthe tapered tip of the tubular body member, the plurality of holes beingformed through the wall thickness of the tubular body member and incommunication with the lumen to define an array of diffusion holes. 2.The peripheral catheter of claim 1, wherein the plurality of holescomprises a plurality of staggered holes formed through the wallthickness of the tubular body member an in communication with the lumento define a staggered array of diffusion holes.
 3. The peripheralcatheter of claim 1, wherein the tapered tip is tapered to a diameterthat is less than the predetermined diameter of the tubular body member,the tapered tip further including an opening to the lumen.
 4. Theperipheral catheter of claim 1, further comprising a first set of holesdisposed in a first annular ring, and a second set of holes disposed ina second annular ring, wherein the second set of holes is axiallystaggered from the first set of holes from about 15° to about 60°. 5.The peripheral catheter of claim 4, wherein the second set of holes isaxially staggered from the first set of holes about 45°.
 6. Theperipheral catheter of claim 1, wherein the lumen further includes afirst inner wall surface defining a first plane, and each staggered holefurther includes a second inner wall surface defining a second plane,wherein an orientation of the second plane is acute to an orientation ofthe first plane.
 7. The peripheral catheter of claim 6, wherein theorientation of second plane is about 45° relative to the orientation ofthe first plane.
 8. The peripheral catheter of claim 6, wherein anorientation of the second plane relative to the first plane is fromabout 15° to about 75°.
 9. The peripheral catheter of claim 6, furthercomprising a first set of holes disposed in a first annular ring, and asecond set of holes disposed in a second annular ring, wherein thesecond set of holes is axially staggered from the first set of holesfrom about 15° to about 60°.
 10. A method for manufacturing a peripheralcatheter for diffusing an infusant, the method comprising: providing atubular body member having a predetermined diameter and wall thickness,the tubular body member further having a proximal end, a distal end anda lumen extending therebetween, the tubular body member further having atruncated length sufficient to access a peripheral vein of a patient;tapering the distal end of the tubular body member to provide a taperedtip; and forming a plurality of holes through the tapered tip of thetubular body member and in communication with the lumen to define anarray of diffusion holes.
 11. The method of claim 10, furthercomprising: disposing a first set of holes in a first annular ring;disposing a second set of holes in a second annular ring; and axiallystaggering the first set of holes from the second set of holes fromabout 15° to about 60° to provide a staggered array of diffusion holes.12. The method of claim 11, further comprising axially staggering thefirst set of holes approximately 45° from the second set of holes. 13.The method of claim 11, further comprising positioning an inner wallsurface of each staggered hole to an angle that is acute to an innerwall surface of the lumen.
 14. The method of claim 13, wherein the angleof the inner wall surface of each staggered hole is about 45° relativeto the inner wall surface of the lumen.
 15. The method of claim 14,further comprising: disposing a first set of holes in a first annularring; disposing a second set of holes in a second annular ring; andaxially staggering the first set of holes from the second set of holesfrom about 15° to about 60° to provide a staggered array of diffusionholes.
 16. The method of claim 15, further comprising axially staggeringthe first set of holes approximately 45° from the second set of holes.17. The method of claim 13, wherein the acute angle is from about 15° toabout 75°.
 18. A peripheral catheter, comprising: a tubular body memberof a predetermined diameter and wall thickness, the tubular body memberhaving a proximal end, a distal end and a lumen extending therebetween,the tubular body member further having a truncated length sufficient toaccess a peripheral vein of a patient, and the lumen further including afirst inner wall surface defining a first plane; a tapered tip formingthe distal end of the tubular body member; and a plurality of holespositioned on the tapered tip of the tubular body member, plurality ofholes being formed through the wall thickness of the tubular body memberand in communication with the lumen to define an array of diffusionholes, each hole further including a second inner wall surface defininga second plane, wherein an orientation of the second plane is acute toan orientation of the first plane.
 19. The peripheral catheter of claim18, wherein the orientation of the second plane is about 45° relative tothe orientation of the first plane.
 20. The peripheral catheter of claim18, further comprising a first set of holes disposed in a first annularring, and a second set of holes disposed in a second annular ring,wherein the second set of holes is axially staggered from the first setof holes from about 15° to about 60° to provide a staggered array ofdiffusion holes.
 21. The peripheral catheter of claim 20, wherein thesecond set of holes is axially staggered from the first set of holesabout 45°.
 22. The peripheral catheter of claim 18, further comprisingan elongate gap disposed between an upstream hole and a downstream hole.23. The peripheral catheter of claim 20, further comprising a third setof holes disposed in a third annular ring, wherein the third set ofholes is axially staggered from the second set of holes, and the firstset of holes is axially aligned with the third set of holes.